In the art of higher efficiency transportation vehicles, vehicle weight is known by elementary physics and experience to be the strongest variable influencing fuel consumption. After losing 75% of the combustion energy to waste heat, current vehicles waste 95% of the remaining energy to moving the vehicle mass, resulting in an overall efficiency of just 2% in performing the desired function of moving the occupants. The waste heat loss is directly coupled to vehicle mass (engine and drivetrain size are proportional to vehicle mass per performance requirements).
In prior efforts to reduce vehicle weight automobile manufacturers developed “body-integral” design methodology, which merges the vehicle frame into the vehicle body structure, industry labeled as the “body-in-white”. This improved on the prior “body-on-frame” methodology that was traditionally used for the design of American-manufactured automobiles and trucks up until the mid 1980s. However, the “body-integral” approach appears to have reached a threshold at approximately 2800 pounds, explaining the minor increase in fuel efficiency offered by currently advertised “high efficiency” vehicles. This may be understood in the current automobile manufacturer's method and use of continuous thickness sheets of metal which are then stretched into shape by molds, incurring use of material where the strength is not needed. Use of lighterweight materials offer some advantage, however, this impacts cost, negatively impacting the ultimate goal of lower total cost-of-ownership. Further, automobiles continue to be designed for 4-5 occupants negatively impacting vehicle weight. The wheels and tires of present 4-wheeled vehicles limit the extent of vehicle weight reduction and suspension options.
Motorcycles achieve a much more efficient ratio of vehicle-weight to passenger-weight. However, motorcycles, are market-limited, primarily used for enjoyment riding, as they do not provide a closed occupant configuration to provide additional safety to the occupants and to protect the occupants from the weather elements. Three-wheeled motorcycle variants with enclosures have been introduced with limited marketability, presumed due to poor experience with 3-wheeled ATVs (all terrain vehicles) and their subsequent forced market removal. Motorcycle frame construction is of the assembly of tubular steel and other irregular formed steel shapes.
U.S. Pat. No. 5,729,463 Describes a method for designing and producing light-weight automobile bodies, but this patent is focusing on applying various techniques aimed at reducing the mass of the current “Body-in-white” (car manufacturer terminology) structural design methodology. It does not consider a narrow vehicle with a roll-cage structure or a cambering chassis.
U.S. Pat. No. 4,045,075 describes a light-weight vehicle and body envelope construction for an “elongated wheel-based vehicle of relatively “narrow” track where the aspect ratio for wheel base to track is approximately 2:1 and 3:1. It states that the light-weight vehicle approach taught herein relies upon a central truss member within the passenger compartment which extends longitudinally and symmetrically between the wheel mounting positions as the main longitudinal bending load bearing member of the vehicle. The body frame is made from tubular aluminum construction, and the vehicle configuration drawings indicate a larger vehicle type, with 3 rows of seating, and 2 passengers positioned side-by-side per row of seating. The frame structure calls for an elongated wheelbase (comparable to American vehicles from the 1960s), and is aimed at providing a larger light-weight vehicle that overcomes the inferior ride and comfort characteristics associated with small, short wheel based vehicles know as sub-compact cars. The vehicle configuration consists of a frontal track and width of a sub-compact car, but with a significantly elongated vehicle length and a much longer wheelbase. The vehicle dimensions specify a wheelbase of 156 inches, a track width of 54 inches, an overall length of 224 inches, and a height of 48 inches. While this configuration would result in a vehicle weight that is lighter than the conventional body-integral structural design, it represents a comparatively large vehicle that is much heavier than the described invention. U.S. Pat. No. 4,045,075 does not refer to any wheel construction or type, nor does it impart specific motion or fuel efficiency improvements.
U.S. Pat. No. 4,087,106 Describes a 3 point cambering vehicle having a steerable front contact and laterally spaced rear contacts all engaged for cambering and continuous engagement with a support surface during cornering and other maneuvers. The configuration presents a 3-wheeled, human powered tricycle, with cambering to be actuated by the operator via standing and shifting weight in a natural manner on left and right foot pads secured to the respective free ends of the trailing arms. This 3 wheeled tricycle design is configured with the operator in a standing position, and uses small wheels.
U.S. Pat. No. 6,449,554 Describes a travel speed controller for an electrically-powered light-weight vehicle having a 2-wheeled scooter type configuration with the operator in a seated position. The focus is on the electronic travel speed controller for an electric vehicle, wherein the electronic sensor memorizes acceleration speeds and can accelerate the vehicle with no aid from an accelerator or foot pedals. Wheel and tire type, and any unique methodology related to type and operation is not discussed.
U.S. Pat. No. 4,732,819 Describes a light-weight, powered vehicle frame structure using a tubular frame construction for a 3-wheeled, 2-passenger type of vehicle. The invention claims to eliminate the problems attendant to conventional pipes used as a structural member adapted for light-weight vehicles such as motorcycles, and for small three or four-wheeled vehicles used for economic transportation or as off-road vehicles. The intent of the patent is to provide a vehicle body with a structural member that allows an outer plate to serve as a reinforcement member in the vehicle body frame of a light-weight vehicle and reduce the weight of a vehicle body construction. The configuration of the vehicle uses 2 front wheels and a single rear wheel design. The occupant configuration is for an operator in the front single seating position with a passenger in a rear single seating position.
US Patent 20060237242 Describes a light-weight surface vehicle using a multiplicity of modular light-weight vehicle sections to effect configurations, anywhere from a bus, to multiple-linked buses, to personal transportation in the form of a vehicle or bicycle. It describes the use of a serial hybrid propulsion system using and internal combustion engine of varying types and fuel sources, a generator, electric motors, utilizes a pulley belt gear ratio mechanism, and includes hydraulics for steering and brake systems, and an air compressor for better ride control. It additionally, discusses the use of bicycle or motorcycle wheels to achieve a light-weight vehicle configuration.
The development and market presence of current hybrid vehicles is an effort to increase fuel efficiency without changing the current vehicle platform. While market savvy, this approach is quite limited in fuel efficiency improvement; in view of the established relationship of fuel consumption to vehicle mass (EPA data: 1 gallon 1100 miles 1900 pounds). Beyond minor improvement in fuel economy over 25 years (1982 Honda Civic, 1500 pounds, actual 40 mpg, and a 2007 Prius, 2987 pounds, actual reported 42 mpg), FIG. 10 data exposes that if the “heavyweight” hybrids were corrected for having marketable, and comparable acceleration to their conventional counterparts, their resulting fuel economy would align with that of conventional vehicles. Viewed alternatively, the same fuel economy-acceleration performance could be achieved more simply by reducing the vehicle weight, including elimination of hybrid components. It is clearly important that hybrid drivetrain mass impact be examined in order to achieve market improvement in fuel economy.
Energy storage in hybrid drivetrains has incurred significant additional mass to the vehicle. In particular battery-based storage systems are comparatively low in power density (200 to 400 Wkg for today's advanced types), however, they are high in energy density (200 W-hrkg). In addressing the power demands and overcoming poor charge and discharge efficiencies (70-90% dependent upon technology and state-of-charge (SOC)), battery mass becomes a significant weight contributor. Excessive energy storage has led to hybrid designed for long cycle times (lengthy discharge and charge times).
The inability of batteries to charge and discharge at high rates and high efficiencies, has been an impetus to augment the storage with higher power density medium. e.g. ultracapacitors (−6000 Wkg) for the high rate conditions. Unfortunately the combination of batteries and ultracapacitors brings about other limitations, as well as added costs, complexity and reduced reliability. For a series combination of batteries and ultracapacitors, the battery limits the current rate, so little improvement in charge/discharge rate occurs. When used in parallel, the ultracacapacitors, whose characteristic voltage change is stronger than the battery for a given charge/discharge rate, the battery limits the capacity use. A pure ultracapacitor storage solution was not envisioned for automobile application, as ultracapacitors are too low in energy storage (<lo W-hr/kg) to accommodate the mass-driven requirements of the current automobile platform.
Others have identified approaches with switched banks of UC's, or in combination with batteries, to avert the extreme voltage reduction that would be experienced by continuing to draw from a single UC. However, this methodology results in significant underutilization of the capability of the UCS (typically less than 50% as voltage input variations are limited to 2:1 for many devices). The additions of banks (either battery or UC) bring increased switching components/complexity, efficiency loss, increased weight (reducing vehicle efficiency) and cost.
U.S. Pat. No. 6,265,851 describes an electric vehicle power system for a semiconductor wafer handling application, having ultracapacitors and batteries as parallel sources connected to a source-selecting switch and having said switch direct its output only to a DC-DC converter which serves the motor load, however, this incurs the converter losses when no conversion is necessary.
Laid open US Pat App. US 2004/0100149 describes topologies for multiple energy sources, including UCs, and accommodates reverse power flow from the utility being driven (case of regenerative braking for a transportation vehicle). In the described topologies, all power is continuously directed through a power converter module, with inherent losses and limitations per device sizing.
U.S. Pat. No. 7,004,273 discusses a bank of ultracapacitors directly bussed to an engine-driven generator with a control management unit bringing the engine on and off to maintain the state-of-charge of the ultracapacitors. This approach does not address the inefficient ultracapacitor capacity utilization issue, resulting in extensive burden/cycling of the engine and/or significant oversizing of the ultracapacitor bank.
U.S. Pat. No. 7,109,686 describes the use of braking resistor and switch structure to assist in charging and discharging an ultracapacitor bank and to protect the ultracapacitor from excessive pre-charge current. A DC-DC converter is referenced as expensive, and its use is referenced only as an alternative method to pre-charge the ultracapacitor hank. While low in cost the use of the braking resistor diverts energy, thereby wasting said energy.
A solution which could extract more of an ultracapacitor's capacity would greatly assist in reducing wasted capacity and enable an all-ultracapacitor storage solution for a lightweight vehicle. Augmentation with thermal-to-electric recovery of waste heat furthers this potential.
The opportunity afforded by improving the thermal efficiency of internal combustion engines (ICE) (commonly 28% for gasoline, 34% for diesel engines) is well understood, however longstanding research and development efforts have not produced marked technical and/or market impacts. Turbo-charging and ceramic insulation of combustion chamber components have made the most significant impact, however, cost and the extent of efficiency improvement (−10%), has not led a to significant reduced fuel consumption on a functional work unit basis, and accordingly not impacted the per capita basis. Exhaust gas turbines with mechanically-connected generators have been presented as alternative, however, cost and efficiency have similarly preempted commercialization. Thermal-to-Electric devices and systems have also been presented to capture the waste stream energy, however, the device efficiencies for prior thermoelectric and thermionic cases, have been very low (<lo %), limiting the use to lesser power applications. Efficient use of prior devices were also limited to very high temperatures, typically requiring >700° C. The design of the thermal transfer system encapsulating the thermoelectric or thermionic devices have lacked adequate transfer surface and residence time, resulting in reduced energy extraction from the bulk stream.
In the case of transportation vehicles, having proliferated a high-mass (high load) basis contributes to the magnitude of the loss, and increases the magnitude and cost of thermal recovery options. Higher fuel prices have inspired the market for vehicles with hybrid drivetrains (ICE assisted by a generator (s) with energy storage system, yet the approximate 70% wasting of exhaust energy continues in these systems as well.
U.S. Pat. No. 4,148,192 describes a “parallel” internal combustion electric hybrid powerplant having thermoelectric devices positioned in such manner as to receive heat energy from the engine exhaust and deliver electrical energy to the system's battery. The thermal conversion elements are attached to the exterior surfaces of the exhaust pipe and the cylinder walls.
U.S. Pat. No. 4,489,242 Discusses the use of a stored energy system to provide the necessary energy for operation of a vehicle's accessories, and includes a suggestion for an exhaust-driven thermoelectric unit, amongst a multitude of options (without detail sufficient to build or determine viability of such an approach).
Laid-open application US200610000651 describes the same invention of the former U.S. Pat. No. 4,148,192
U.S. Pat. No. 5,857,336 Describes an exhaust-driven turbo-assisted positive displacement engine for a hybrid electric vehicle, and having a second exhaust passage with another turbine which mechanical turns a (mechanical) generator to recover additional energy when the waste-gate bypasses the first turbo.
U.S. Pat. No. 7,100,369 describes a thermoelectric device system extracting heat from the exhaust stream of an engine having a primary and secondary exhaust passages and control valves operated based upon engine load for optimization.
U.S. Pat. No. 6,605,773 presents a thermoelectric generator for a fuel-cell power plant of a vehicle, having a thermally-activated regulator controlling the heat source (fuel cell) and/or the cooling medium to the generator, thereby eliminating the cost and complexity of a DC-DC converter.
U.S. Pat. No. 7,068,017 describes a source regulation (impedance transformation) electrical system used to increase the efficiency of power transfer from a direct energy source (one example, of many, and not described with sufficient detail as to allow construction or viability) being a thermoelectric or thermionic device) to the load.
U.S. Pat. No. 7,111,465 presents improved thermoelectric generator design by thermal isolation of thermoelectric devices in an array.
Laid-open application US200510204762 presents a thermoelectric generation system interfaced to the combustion exhaust stream via a heatpump with liquid circulation system having an endothermic reaction.
Laid-open application US200510204733 presents the invention of the former US200510204762 with the introduction of the catalytic treatment of the exhaust, and options for integration and optimization with the thermoelectric system.
Laid-open application US200510074645 describes a thermoelectric generating system capturing heat from a solid oxide fuel cell, the generating system having a vacuum enclosure surrounding the thermoelectric devices (for thermal isolation).
There exist technical, approval agency, and marketing issues to overcome in achieving market success of a safe lightweight vehicle. The U.S. Department of Energy has concluded that the U.S. automakers “have the public convinced that high vehicle mass is required to be safe”. Automobile collision fatality data indicates that incompatible bumper heights, causing “under-run” and “over-run” conditions are the predominant issues (personnel protection is highly diminished when the primary impact device is averted). The same federal standards exempt SUVs, pickups and minivans from standard 215 compliance, the very vehicles that are cause for the incompatibility and the resulting extent of damage and injury.
The present invention eliminates the foregoing problems attendant to conventional vehicle body construction methods that result in heavier vehicles, and from motorcycle shortcomings for occupant protection through the design and construction of a safe, light weight, and super-efficient four-wheeled vehicle using large diameter constant-radius wheels, and a short-cycling serial hybrid drivetrain with exhaust heat recovery of energy.